Re: [GENERAL] aggregate returning anyarray and 'cannot determine result data type'

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Tomas Vondra <tv(at)fuzzy(dot)cz>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [GENERAL] aggregate returning anyarray and 'cannot determine result data type'
Date: 2014-04-26 20:32:27
Message-ID: 14692.1398544347@sss.pgh.pa.us
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Tomas Vondra <tv(at)fuzzy(dot)cz> writes:
> On 25.4.2014 23:26, Tom Lane wrote:
>> The problem is that the CREATE AGGREGATE syntax only specifies the
>> name of the final function, not its argument list, so you have to
>> make an assumption about the argument list in order to look up the
>> final function in the first place.

> Yeah. And it wouldn't be clear which function to use in case two
> suitable functions (with different signatures) exist. So I guess this
> actually requires a parameter.

Exactly.

> I'd vote for "finalfunc_extra" - can't think of a better name, and I'm
> not sure what the "m" in "mfinalfunc_extra" stands for.

Sorry for not being clear. The "m" version is the alternate setting for
the moving-aggregate sub-implementation, which is new as of a couple weeks
ago:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=a9d9acbf219b9e96585779cd5f99d674d4ccba74

regards, tom lane

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